1. Field of the Invention
The present invention relates to a band feed length adjusting device in a packing machine, and more particularly to a band feed length adjusting device in a semi-automatic packing machine which can feed a band having a proper length at a next banding operation if a fed band is short.
2. Description of the Related Art
For example, as shown in FIG. 4, a semi-automatic banding packing machine comprises a band reel 1 provided under a packing machine body 4. A band led from the band reel 1 is caused to pass through a suspension roller 2 and then through a roller 3 of a brake arm and is thereafter inserted in a hole 5 provided on the packing machine body 4. In this manner, a first band insertion is carried out.
In such a semi-automatic machine, the packing machine body 4 includes band feeding means A having a driving roller 7 and a touch roller 9 and band returning means B having a driving roller 8 and a touch roller 10 as shown in FIG. 5. In the semi-automatic machine comprising such a band feeding device, when one of the means is driven, the other means is stopped. Thus, the band can freely be moved between the rollers on the stop side.
In order to carry out banding, when a band feeding switch 14 is first turned on, the operation of the band feeding means A is started in response to an instruction signal sent from a controller so that a band having a predetermined length is pushed out toward the upper surface side of the packing machine body 4. Then, the tip of the band thus pushed out is wound upon the periphery of an object to be packed and is inserted into the packing machine body. Consequently, the tip of the band abuts on a limit switch provided on the band feeding device in the packing machine body so that operation of the band returning means B is started and the band is then returned in a reverse direction. Thus, the band is consecutively returned and tightened.
In addition to such a structure that permits the band to be fed by means of two roller pairs and then returned and tightened, a band feeding device is also known in which the band is fed and returned and tightened by means of one roller pair. For example, as shown in FIG. 6, a driving roller 11 is constructed to be reciprocally rotatable and a touch roller 12 abuts the roller 11 so that the band can be selectively fed and tightened by means of a roller pair.
In a conventional semi-automatic banding machine, the feed length of the band by the band feeding means A is typically adjusted by controlling by means of a timer a time required for rotating the driving roller 7.
However, an object to be packed has various sizes. Accordingly, if an object to be packed having a certain size is banded and a next object to be packed having a larger size is to be then banded, the band having a current feed length cannot be wound upon the larger object to be packed. In that case, conventionally, the band shortage has been adjusted by manually pulling out the tip of the band without changing the set time of the timer.
However, even if the length of the band is thus adjusted, a countermeasure is taken only once. Therefore, also in the case in which the banding is to be subsequently carried out, only the band having a current small length is fed. Accordingly, the length of the band is still insufficient. Therefore, the insufficient part should be led out again.
In consideration of the above-mentioned circumstances, it is an object of the present invention to provide a band feed length adjusting device in a packing machine which can newly input, to a control section, a value obtained by manually leading out a band to adjust the feed length of the band at a first work and can subsequently feed the band having a correct length in the case in which the size of an object to be packed is changed to be larger.
In order to achieve the above-mentioned object, the present invention provides a band feed length adjusting device in a packing machine in which
a plurality of detecting portions are provided at regular intervals on a side surface of a touch roller which is opposed to a normal rotating roller or a reverse rotating roller and serves to selectively abut on one of the two rollers, thereby constituting band feeding means or band reverse rotating means, and furthermore,
a sensor for detecting the detecting portions is provided to face an outer periphery of the touch roller,
wherein when an amount of the band led from a band reel through a driving operation of the band feeding means for winding onto an object to be packed is insufficient, the band having a length corresponding to the shortage is led from the band reel through a manual operation and
the detecting portions of the touch roller thus moved are detected by the sensor and a result of the detection is supplied to a control section, thereby automatically adjusting a band length required for subsequent band feeding.
According to the present invention having the above-mentioned structure, it is possible to measure the shortage of the length of the band led out by means of the sensor. Consequently, if the shortage of the length of the band is newly input to the control section, the band having a length correctly set can be subsequently fed.
As described above, in the band feed length adjusting device in the packing machine according to the present invention, the amount of the band to be led out is automatically calculated through the rotation of the touch roller and is added to the feed amount for the subsequent banding. Therefore, in the case in which the size of the object to be packed is changed to be larger, the band feed length can be adjusted automatically.
These objects as well as other objects, features and advantages of the present invention will become more apparent to those skilled in the art from the following description with reference to the accompanying drawings.